Interpretive Summary: Genetic factors contribute to the differences among people when comparing how they respond to the vitamin K-antagonist, warfarin. These differences in warfarin sensitivity among individuals may be explained by the role various genes have in influencing vitamin K status. We genotyped 415 older men and women, aged 60 to 80 years and primarily of European descent, for common polymorphisms in two genes that influence vitamin K, VKORC1 and GGCX. We then examined for associations between polymorphisms and biochemical markers of vitamin K. Individuals with the least common polymorphism for VKORC1 had significantly higher vitamin K status than those individuals with the more common polymorphisms. Cross-sectional analyses also revealed that individuals who were heterozygous carriers of GGCX gene may have improved vitamin K function. Polymorphisms in genes encoding enzymes involved in vitamin K metabolism may modulate vitamin K status.